I just brought a 2001 Focus 1.6 Zetec and the radio doesn't work properly. It works perfectly for about a minute then the ere sound of white noise settles in and it won't pick up anything. Restarting the radio does nothing, it's only when I come back after a few hours and it works again for a short moment. So is this a real problem or am i just doing somthing stupid?

There is the connector on the rear of the radio and usually one behind the drivers side A pillar trim also.
Tbh I'd suspect the A pillar one as that's probably where they would disconnect from when the dash comes out.